Pseudomonas Septicemia: causes, symptoms and treatment

Pseudomonas Septicemia (Pseudomonas fluorescens) — etiology, symptoms, diagnosis, active-substance medication, recovery and prevention; mortality without treatment: high.

Overview

Opportunistic Gram-negative pathogen causing fin rot, skin ulceration, and systemic infection in stressed fish. Often co-infection with Aeromonas. Causative agent: Pseudomonas fluorescens. Transmission: water. Incubation: 2-10 days. Reported mortality without treatment: high.

Symptoms

• red streaks on body and fins
• fin rot
• ulceration
• hemorrhages
• lethargy
• fluid accumulation in body cavity

Causes

Outbreaks are typically triggered by chronic stress, poor water quality, temperature swings, overcrowding, or the introduction of unquarantined fish. The pathogen spreads via free-swimming or waterborne stages in shared water.

Diagnosis

Diagnosis is based on clinical signs (lesions, hemorrhages, behaviour) combined with bacterial culture and Gram-staining where available. Differentiate from co-infections with other Gram-negative pathogens; antibiotic sensitivity testing improves treatment success against Pseudomonas fluorescens.

Treatment

Effective treatment requires isolating affected fish in a quarantine tank, identifying the pathogen, administering the appropriate active substance at the correct dose and duration, and supporting recovery with stable water parameters and nutrition.

Step 1: Quarantine

Set up a bare-bottom quarantine tank with a mature sponge filter, heater, and aeration. Match temperature and pH to the display tank, and acclimate fish slowly. A bare bottom simplifies daily siphoning and prevents medication from being absorbed by substrate.

Step 2: Medication

1. Kanamycin + furan combo. Kanamycin + nitrofurazone in QT for 7-10 days; address underlying water quality and stressors. (duration: 7-10 days)

Step 3: Recovery

After medication, perform a 30-50% water change and run fresh activated carbon for 24-48 hours to remove residues. Continue feeding a high-quality, varied diet with vitamins and immunostimulants. Reintroduce fish to the display tank only after at least one week without recurrence of symptoms.

Prevention

• pristine water quality
• minimize stress
• quarantine new fish
• stable temperature
• balanced nutrition